Current spatial light modulators used in the art have relatively thick photoconductors and utilize a two electrode structure. Because of the thickness of the photoconductor, the spatial resolution is in many cases very limited with this prior art structure. These prior art devices include devices made with CdS or crystalline silicon. In devices of this type, in order to improve resolution, the speed or contrast is usually affected. In the case of crystalline silicon, a rather complicated integrated circuit is required in the surface of the photoconductor. Other photoconductor materials such as bismuth silicate (BSO) get around the problem of thickness limited resolution due to the very high resistivity of the material. However, in this case, the photoconductor material is a carefully grown single crystal and is therefore difficult to fabricate and produce in large sizes as well as being expensive to produce. Therefore, it can be seen that a more easily reproducable and compact modulator is needed.
Accordingly, it is an object of this invention to provide an amorphous silicon spatial light modulator that utilizes a three electrode structure to provide a more efficient device.
Another object of this invention is to provide a modulator that has three electrodes to add additional dimension to the control of the electric field.
Still another object of this invention is to provide a modulator in which very thin types of photoconductors can be used and yet provide large modulation effects.
A still further object of this invention is to provide a device in which a very thin amorphous silicon layer can be used with nematic types of liquid crystals.
Other objects and and advantages of this invention will be obvious to those skilled in this art.